The metal band production units generally comprise several sections with different functions, such as hot rolling, etching, cold rolling and finishing.
Even if, in some cases, some sections can be gathered, it is generally necessary to wind the band into a coil, at the outlet of a section, in order to convey it to the following section.
To this end, a coiler is used, comprising a chuck constituted of a shaft brought into rotation around its axis and on which can be fixed, in a removable way, the end of the band. By rotation of the chuck around its axis, the band is wound around the chuck, into superimposed spires, until completion of a coil.
Most often, the chuck extends cantilever from a frame carrying the rotation driving means of the chuck and is provided with a system enabling to pull it backwards to allow retraction of the coil.
Generally, the band is maintained under traction in order to tighten the spires. When the coil reaches the requested diameter, corresponding to a certain band length, it is withdrawn from the chuck.
After withdrawal of the coil, the leading edge of the following band is caused to reach the chuck and the operation can resume.
Retraction of the fully wound coil and the beginning of the winding operation of the following coil causes a down-time whose duration should be kept to a minimum. Indeed, it is preferable not to interrupt the passage of the band in the treatment unit upstream of the coiler and we are therefore led to connect the said treatment unit to a buffer system whose capacity depends on the down-time necessary to changing the coil.
To reduce this down-time, it has been suggested to use a so-called &lt;&lt;revolver-type coiler&gt;&gt; unit, comprising a revolving mounting, able to rotate around a central axis on a fixed frame and on which are fixed at least two chucks extending cantilever on a same side of the mounting from an embedded end. Each chuck can be brought into rotation around its axis which is parallel to the central axis.
By orienting the revolving mounting, each chuck can be placed in at least two successive positions. In a first winding starting position, the leading edge of the band is attached onto the chuck and the rotation of the latter is controlled in order to wind the band over a certain number of spires. Then, by rotation of the revolving mounting, the first chuck, while winding, is brought into a second position enabling to complete the winding of the band. At the same time, by rotating the revolving mounting, the second chuck is placed into the first starting position, thus waiting for the subsequent operation.
Thus, when the requested length of the band has been wound around the first chuck, it is cut off along a shearing line perpendicular to the passage direction and the ends of the band located upstream of this shearing line which constitutes the leading edge of the following band, can be attached immediately onto the second chuck in a waiting position in order to start the winding of the following band during the time necessary to unloading the coil which has been completely wound.
The first chuck is then released and may come back, by rotation of the mounting, into the first starting position. At the same time, the second chuck, on which the first spires have been wound, is placed into the `completed winding` position.
Such a &lt;&lt;revolver-type coiler&gt;&gt; thus enables to reduce the downtimes considerably.
Obviously, other arrangements are possible and, for instance, the coiler could comprise three chucks brought successively, by rotation of the mounting, into a first starting position, a second complete winding position and a third unloading position.
As stated, each chuck extends, normally, cantilever, from the revolving mounting in order to enable the retraction of the coil after winding, by sliding axially towards the side opposite to the mounting. However, since the coil is very heavy, it is preferable during the winding operation, that the end of the chuck opposite to the mounting rests on a removable counterbearing.
In the single-chuck coilers, the counterbearing is simply placed on a retractable bracket forming a chair resting on the ground or on a section of the fixed frame.
Upon completion of the winding operation, the supporting chair is taken away from the chuck to enable the retraction of the coil.
In revolver-type coilers, it is also possible to use a removable counterbearing mounted in a supporting chair which is arranged in the complete winding position, in order to support the chuck up to the completion of the winding operation, i.e. when the coil is the heaviest. Conversely, the chuck in the starting position is generally left idle and its end which is embedded in the revolving mounting, is subjected to important loads caused by the weight of the coil which increases gradually and, besides, to the traction load which must be modulated according to the diameter and which is particularly high at the beginning of the winding operation.
Obviously, it would be possible to connect a second supporting chair to the chuck in starting position, but such a device would be rather cumbersome and, anyway, would provide a rest for the chuck only for winding the first spires, since the chuck remains cantilever during its rotation, from the starting position to the complete winding position.
The purpose of the invention is to overcome these shortcomings thanks to a new arrangement enabling to support the chuck in all the positions and, even during the rotation of the revolving mounting.